package sort;

public class quickSort {
    public static void main(String[] args) {
        int arr[] = {3,9,-1,10,-2};
        sort(arr);
        for (int a:arr) {
            System.out.println(a);
        }
    }
    public static void sort(int[] arr) {
        if (arr == null && arr.length < 2) {
            return;
        }
        sort(arr, 0, arr.length - 1);
    }

    public static void sort(int[] arr, int l, int r) {
        if (l < r) {
            swap(arr, l + (int) Math.random() * (r - l + 1), r);
            int[] p = partition(arr, l, r);
            sort(arr, l, p[0] - 1);
            sort(arr, p[1] + 1, r);
        }
    }

    public static int[] partition(int[] arr, int l, int r) {
        int less = l - 1;
        int more = r;
        while (l < more) {
            if (arr[l] < arr[r]) {
                swap(arr, ++less, l++);
            }
            if (arr[l] > arr[r]) {
                swap(arr, l, --more);
            }
            if (arr[l] == arr[r]) {
                l++;
            }
        }
        swap(arr, more, r);
        return new int[]{less + 1, more};
    }

    public static void swap(int[] arr, int l, int r) {
        int temp = arr[l];
        arr[l] = arr[r];
        arr[r] = temp;
    }
}
